Abrasive wheel



Jan. 14, 19-64 1', J, MARTlN 3,117,40

ABRASIVE WHEEL i Filed Aug. 6, 1962 United tates Patent O H1409 ABRASl-I WHEEL Thomas l. Martin, 22 W. St., La Grange, lli. Filed Aug. 6, @i629 Ser. No. 214,922 i Claims. (Ci. :El-269) The present invention relates to an abrasive v/heel and more particularly it relates to an improved abrasive wheel that is self lubricating and sel-f dressing.

In conventional grinding operations lubrication is not a real problem since the lubricant, which may be water, oil or other suitable lubricating material, is directed at the interface between the grinding wheel and the work being ground. Some cooling methods `for the wheel involve playing a stream of coolant upon the wheel at a point remote from the working interface to keep the wheel cool. Various other lubricating methods also are used, most of which involve directing a lubricant into the interface between the Wheel and the piece being ground.

Most of the lubricating methods known result in an overspray of lubricant and general or partial blocking of the view of the piece upon which the work is being performed. rthis occlusion of the view of the work piece is unacceptable where it is necessary to place a precise iinish upon the piece or where the work is of a detailed nature and obliteration of the view by a lubricant would result in a generally unsatisfactory working condition. ln View of this, diamond grinding of the nish upon cutting tools or the like normally has been done dry without the benefit of lubrication or cooling in order to prevent any blocking of the view of the piece upon which the work is being performed. -Dry grinding, of course, results in premature deterioration of the grinding wheel and can cause burning of the piece upon which the work is be'mg performed due to overheating. Undue thermal stresses may also be set up in the piece due to the moderately high temperatures generated during the grinding operation due `to the frictional resistance between the abrasive and the piece. An independent external coolant may not be added for the same reason that lubrication is avoided, namely, that the coolant would possibly block the view of the piece being worked upon.

Additional disadvantages are inherent in the provision of external lubricating and lubricating means in that the flow of lubricant and coolant must be adjusted in accord with predetermined practices to provide for suiicient cooling capa-:ity without unnecessary occlusion of the view of the piece being Worked upon. Further, separate reservoirs and liuid conduction means rnust -be provided for the iiuid coolant and lubricating systems and thus an additional inconvenience is introduced.

lt can readily be seen that it would be convenient to provide a grind-ing wheel that carried its own lubricant for release onto the grinding surface during the grinding operation.

A further inconvenience in grinding `operations involving diamond abrasive wheels arises from the yfact that it is the common practice to provide a synthetic resin or metal base Wheel for the diamond abrasive grinding section. The plastic or metal base wheel are attractive to wheel :manufacturers in that they are convenient and economical to manufacture and are easily handled. However, `the tenacity of these body materials and their continuous physical structure give rise to frequent interruptions in the grinding operation to cut back or dress these materials away from the diamond grinding surface in that they do not abrade as readily as the diamond abrasive area but rather flow and eventually impair the eiciency of the ydiamond abrasive section in that these materials will flow into the interstices between the abrasive particles.

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in accordance with the present invention an abrasive heel is provided that is self lubricating and that requires little or no supplementary dr-essing. The base wheel is provided of a granular abrasive material that is porous when formed. A suitable lubricant is disposed within the porous body or interstices between the individually bonded granules of abrasive material. The lubricant is of a character that is solid at ambient temperatures and that becomes viscous lor fluid at working temperatures of the wheel so that it will, during the grinding operation, ow in .a relatively thin viscous film over the grinding surfaces and thereby provide a non-ocoluding lubrication for the ywheel and work piece. The abrasive body of the base wheel is of a material that will abrade or wear away quicker lthan the diamond grinding section of the wheel and thus the surfaces adjacent the Working portion of the grinding wheel are always Idressed to at least co-planar relation with the working portion of the abrasive wheel.

lt is, therefore, a general object of the present invention to provide an improve-d self-lubricating self-dressing abrasive wheel.

A further object of the present invention resides in the provision of a diamond abrasive wheel that is sclf-lubri eating.

Still another object off the present invention resides in the provision of an improved abrasive wheel having a Idiamond grinding surface wherein the body of the supporting -wheel is of a granular abrasive material.

A further object yof the present invention resides in the provision of an improved abrasive wheel having a diamond grinding surfface and a base wheel of granular abrasive material wherein a lubricating wax is disposed in the interstices of the base wheel adjacent the diamond grinding surface.

Another object of the present invention resides in the provision of an improved abrasive wheel having a lubricating wax interposed .in the interstices of the abrasive portion of the wheel which lubricating wax is solid at ambient Vtemperatures `and viscous at working temperatures.

A further object of the present invention resides in the provision of an improve-d abrasive wheel having a lubricating wax disposed in some of the intcrstices of the wheel body and a lubricating :oil disposed in the remaining interstices of the wheel body.

Generally the abrasive wheel disclosed herein comprises a wheel having a layer of abrasive vdiamond particles bonded to a body section which is composed of a granular, porous abrasive material. The body section in one modification is provided with a plurality of circumferentially spaced openings about the outer periphery of the Wheel adiacent the layer of diamond particles. A wax lubricant is placed in these openings. The wax is of the type that is solid at ambient temperatures and uid or viscous at working temperatures. The heat generated by @frictional resistance between the diamond particles and the piece upon which the work is being performed will serve to heat the wheel body and the Wax lubricant. The lubricant will begin to liow at working temperatures forming a thin viscous film at the work interface to provide a lubricating layer of wax at the interface. The iilm of lubricant `does not interfere with viewing ofthe piece and still provides for effective lubrication of the wheel and the piece upon which the work is being performed.

ln another embodiment of the present invention, a wax lubricant is provided by impregnating a portion of the porous, granular body section of the base or body of the abrasive wheel. The high working temperatures cause the wax to low and the centrifugal force acting upon the wax forces it out into the interface between the grinding wheel and the work piece. A silicone oil lubricant may be disposed in the interstices not occupied by the wax which, for the most part, will be in the area of the wheel away from the grinding surface. The centrifugal action upon the oil will tend to force the wax completely out of the wheel body. When the wax is exhausted, the oil will be available as a lubricant body until the lubricating wax can be replenished.

The novel features which l believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, together with further objects and advantages thereof, wiil best be understood by reference to the following description taken in connection with the accompanying drawings in which:

FXGURE l is a top plan view of an abrasive wheel in accord with the teachings of the present invention;

FIGURE 2 is a cross-section view taken along lines 2-2 of FIGURE l;

FGURE 3 is a top plan View of a modification of the abrasive wheel manufactured in accord with the present invention;

FIGURE 4 is a side elevational view in cross-section taken along lines 4-4 of FGURE 3 and illustrating the relation of the spaced openings about the circumference of the wheel to the diamond abrasive section of the abrasive wheel;

FEGURE 5 is an enlarged fragmentary View of the diamond layer and adjacent spaced opening for wax lubricant; and

FIGURE 6 is a fragmentary view of the abrasive wheel of the present invention in relation to the piece upon which work is being performed illustrating the ow of lubricant into the working interface.

Referring more particularly now to FIGURES 1 and 2 of the drawings, the abrasive wheel of the present invention is indicated generally at llt?. The wheel 1t)l includes a disc-like base portion l2 and a radially extending outwardly flaring wall portion 14. The disc l2 forming the base of the wheel 10 has a centrally disposed opening 16 extending therethrough, said opening being adapted to receive the arbor (not shown) of the powered rotating Imeans (not shown) for directing rotation of the wheel it) during the grinding operation. The arbor and powered rotating means are well known to the art and form no part of the present invention.

TheV wall portion 14 defines an inner and an outer wall surface f3 and 2d, respectively. The wall portion of the wheel shown for purposes of illustrating the invention tapers outwardly from the disc l2 to provide for a shanp outer edge and to allow carefully controlled grinding practices. A tubular shaped wall section rather than the frusto-conical section specifically illustrated would be equally well adapted to use of the invention disclosed herein.

The terminal portion of the outwardly aring wall 14 defines a circumferential surface 22.

The outer wall surface 24)' of the wall portion 14 includes a shallow recess 24 therein extending from the circumferential surface 22 of the wall portion for a short distance inward-ly toward the disc l2 of the wheel 10. F[the base of the recess 24 is generally parallel with the outer Wall Ztl of the wall 14. The recess 24 extends circurnferentially about the upper peripheral portion of the outer Iwal-l 2li of the wall 14,

A layer of diamond abrasive particles 26 is disposed within the recess 24- of the wall 14. The diamond particles 26 are bonded to each other and to the base and wall of the recess 24 to thereby define an integral unit therewith. The outer wall of the diamond particles 25 is substantially in co-planar relation with the wall sur-face 2G of the wall 14. The upper terminal 2S of the diamond layer 26 initially projects a slight distance beyond the circumferential surface 22 of the wheel lt). This provides for contact of only the diamond particle layer with the work piece in use and thereby prevents wear or abrasion by the base or supportwheel adjacent the diamond abrasive layer. It should be observed that the diamond layer cannot extend too far above the surface 2,2- of the wheel since it is unsupported and if considerable grinding pressures will be developed in grinding the layer should not project beyond the surface 22 since the grinding pressures would tend to sever the layer.

A layer of lubricating =wax 36 may be interposed in the interstices between the granular particles adjacent the diamond layer 26 of the wheel. The wax may be heated to fluid temperature and then forced into the inerstices of the upper wall portion 14 adjacent said layer. The wax 30 will cool and harden to fill the interstitial voids. .The wax preferably is disposed only in the portion adjacent the upper terminal of the wheel to a depth adjacent the lower point of the diamond layer as indicated by the dashed line 32 in FIGURE 2. Preferably a synthetic high melting point wax is disposed within the porous openings of the wheel 10. The characteristics of the wax should be such that it is solid at ambient temperatures and uid at or about working temperatures. It should be noted that during the grinding operation with diamond wheels, as presently constructed, temperatures of approximately 50'() degrees Fahrenheit will be realized at the working face and approximately 30G degrees in the adiacent wheel body. The thermal gradients are rather sharp in view of the fact that the plastic body materials normally used in the manufacture of diamond wheels are poor thermal conductors and also a certain amount of air cooling occurs due to the rapid rotation of the wheel. It has 4been. found, during the grinding operation, that the temperatures just below the immediate Surface of the abrasive wheel body of the present invention and adjacent the working interface are approximately 75 to 100 degrees F. less than the diamond grinding surface temperature. ln view of this a synthetic wax such as a diotadeco'yl di amino di phenyl methane may be used in the interstices of the abrasive wheel body. The above noted synthetic Wax has a melting point slightly in excess of 300 degrees F. It can readily be seen that as the grinding surface approaches 40'() degrees F. the lubricating wax will become viscous. The angular rotation of the wheel will develop a determinable centrifugal force tending to expel free particles from the surface of the wheel itl'. The viscous wax 3i) will be urged outwardly toward the surface 22 under the centrifugal action during rotation off the wheel itl and will then be directed to the working interface between the layer of diamond particles and the work piece. The outwardly flaring wall 14 of the Wheel of FIGURES l and 2 will tend to direct the viscous wax lubricant outward-ly with respect to the central axis of the wheel llt). The still viscous wax will ilow to the outer surface of the wheel d@ and thenc along the interface defined between the Workface and the abrasive wheel to then ow over the diamond grinding layer to lubricate thesame. Rotation of the wheel when working is not being accomplished will not effect discharge of the Wax from the wheel body lin that the temperature will not be high enough to precipitate sufficient viscosity of the wax to permit it to flow through the highly tortuous path defined around the granular particles of the wheel within which the wax is disposed.

A lubricating oil such as phenyl methyl siloxane may be disposed below the lubricating wax in the interstices of the body of the wheel 1t) not occupied by the wax to provide an additional reservoir of lubricating means. The oil preferably is located below the wax in that the viscosity of the oil, especially at the elevated temperatures encountered in the grinding operation, will not be prohibitive so -as to prevent the movement of the huid along the tortuous path defined between the granular particles of which the body of the wheel is made. The entire outer surface of the wheel l0, except for the circumferential surface 22, may be coated with a suitable sealant, such as lacquer or the like, to provide an impermeable coating and thereby prevent extrusion of the o-il or wax from any surface other than the circumferential surface 22 of the wheel l0.

A modification of the above described construction is illustrated in conjunction with F-GURES 3 to 5 of the drawings, with the same numbers being used to identify similar portions of the Wheel.

The abrasive wheel is indicated generally at ll. The wheel includes a disc-like base portion l2 and a radially extending outwardly flaring wall portion la. The disc is provided with a central opening 16 to receive the arbor associated with the power means (not shown).

The Wall portion i4 deines inner and outer surfaces 18 and 20, respectively. T he terminal portion of the wall id defines a circumferential surface 22.

As in the form of FIGURE l, the outer wall surface 2i) of the wall 14 is provided with a shallow recess 24 therein extending from the circumferential surface 22 of the wall lli for a short distance toward the disc l2. The radial base of the recess 24 is generally parallel with the outer wall portion 2o of 4the wall i4. The recess extends about the periphery of the Wheel.

A layer of diamond abrasive particles 26 is disposed within the recess 24 of the wall 14. The diamond particles -are bonded to each other and to the abrasive material of the base to define an integral portion of the wheel. The outer portions of the diamond abrasive layer are substantially in mating relating with the adjacent portions of the wheel 14 to provide a continuous wall conformation and circumferential surface conformation.

A plurality of circumferentlally spaced openings 34 are provided about the circumferential surface 22 of tie wall i4 said openings extending into the Wall portion with the axes thereof in substantially parallel relation to the adjacent outer Wall conformation Zit of the Wheel tu. The openings extend into the body of the wall lli to a distance slightly below the lowermost point of the layer of diamond particles. lt should be observed, however, that the depth of the openings 34 is not critical in that it is necessary only to provide sufficient volume for insertion of an adequate amount of lubricant within the openings.

Lubricating wax 39 is inserted into each of the openings dwithin the Wall 14 of the wheel 1t). it should be observed that this form of construction possesses an advantage `over the form of FIGURE 1 in that the wax may be inserted in pencil-like form into the openings 34 without iirst having to heat the wax to fluid temperature. Bars of the wax material may be supplied for severance and insertion into the openings. The openings 34 are adjacent the rear face of the layer of diamond particles 26 of the wheel it). Preferably a high melting point synthetic wax is disposed within the openings 34. The characteristics of the wax should be such that it will be solid at arnbient temperatures and will become viscous or fluid at working temperatures of approximately 300 -R As noted hereinabove, at working temperatures realized during the grinding operation, the wax will become viscous and be able to flow. The wax, in the viscous form, will tend to flow out of the openings 34 under the urging of the centrifugal force acting upon the Wax and will flow in a thin viscous layer over the diamond particle layer deiining the grinding or working surface of the wheel.

As indicated in FIGURE 6, during rotation of the wheel with the work piece against the diamond abrasive layer of the wheel lb, the lubricating wax 3d will tend to be urged outwardly of the openings 34- in a thin viscous film as soon as the temperature of the area within which the Wax is disposed reaches the leve-l wherein the wax becomes viscous. As indicated hereinabove, with the wax noted, this temperature level is approximately 300 IF. yllt should be observed that other lubricating materials may be ernployed that will have similar but specifically dierent thermal characteristics that may be employed with the concept disclosed herein Without departing from the spirit and scope of the present invention. As the Wax ows `outwardly of the openings 34, under urging of the centrifugal force thereupon, it will tend to move over the ou-ter periphery of the circumferential surface 22 of the Wheel it? due to the radially outwardly flaring construction of the preferred form of `the wheel d6. lf any wax should tend to iiy-away from the wheel lltl` due to the centrifugal force, it will strike the work piece 36 and be thrust into the :interface between the work piece and the diamond grinding layer to serve as a lubricant therein. The wax in the viscous form however will tend to flow in a thin film over the diamond particle layer to lubricate the same while at the same time avoiding general obstruction of the view of the operation during grinding.

While I have shown and described a specific embodiment of .the present invention it will, of course, be understood that :other modilications and alternative constructions may be used Without departing form the true spirit and scope of the invention. 1I therefore intend by the appended claims to cover all such modications and alternative constructions as fall within their true spirit and scope.

What l claim as new and desire to secure by Letters yPatent of the United States, is:

l. A self lubricating, self dressing abrasive wheel comprising:

a porous cup shaped base wheel defining a disc portion and a wall portion integral with and extending outwardly from said disc portion, said wall portion having an outer radial surface and a circumferential surface, said circumferential surface being at the outer terminal of the wall portion, the base portion having a central opening extending therethrough, the outer radial surface having a recess therein extending along the outer surface about the entire periphery thereof from the circumferential surface a substantial distance inwardly toward the disc portion of the base wheel;

a diamond abrasive particle section disposed within the recess on the outer radial surface of the wall portion, said diamond particle section being bonded Within the recess of said cup shaped base wheel;

a wax lubricant disposed in the openings of the porous wall portion of the base wheel in the area adjacent the circumferential surface and for a substantial distance inwardly thereof toward the disc portion of the base wheel, said Wax lubricant having the characteristics of being solid at ambient temperatures and owable at working temperatures and adapted at elevated working temperatures encountered during grinding to iiow out over the diamond particle section under the intluence of the centrifugal force encountered during rotation of the wheel to thereby lubrieate the working surface of the particles;

an oil lubricant disposed in the interstices of the wall portion Which are not occupied by said wax lubricant;

and a sealant applied to all the outer surfaces of the base wheel except the circumferential surface to deiine an outer envelope adapted to retain the wax and aid lubricant and to confine their expulsion from the Wheel to the circumferential surface area.

2. A self lubricating, self dressing abrasive wheel comprising:

a porous cup shaped base wheel defining a disc portion and a Wall portion integral with and extending outwardly from said disc portion, said Wall portion having an outer radial surface and a circumferential surface, said circumferential surface being at the outer terminal of the Wall portion, the base portion having a central opening extending therethrough, the outer radial surface having a recess therein extending along the outer surface about the entire periphery thereof from the circumferential surface a substantial distance inwardly toward the disc portion of the base Wheel;

a diamond abrasive material disposed within the recess on the outer radial surface of the Wall portion, said diamond material being bonded to said cup shaped base wheel;

a dioctadecoyl di amino di phenyl methane Wax lubricant disposed in the openings of the porous Wall portion of the base Wheel in the area adjacent the circumferential surface and for a substantial distance inwardly thereof toward the disc portion of the base Wheel, said wax lubricant having the characteristics of being solid at ambient temperatures and flowable at working temperatures and adapted ferential surface of the support member under cen* trifugal action and over the diamond material, said particle defined support member adapted to be depleted at a significantly faster rate than the diamond abrasive whereby the circumferential surface of the support member always is coplanar With or lower than the work engaging face of the diamond abrasive material.

4. In a rotatable self-dressing diamond abrasive cup- 1() shaped wheel adapted to carry and to dispense a thermally responsive lubricant:

a porous cup-shaped support member having a flaring wall terminating in a circumferential surface with a frusto-conical recess defined about the outer peat elevated working temperatures encountered during riphery of the wall and extending to said circumgrinding to flow out in a viscous film over the diaferential surface; mond particle section under the influence of the cena diamond particle abrasive material mutually intertrifugal force encountered during rotation of the bonded and bonded to the recess of said wall to Wheel to thereby lubricate the working surface of the define an integral continuous section with the supparticles; port member and defining a work engaging face in a phenyl methyl siloxane lubricant disposed in the juxtaposed relation to the circumferential surface; interstices of the wall portion which are not occupied and a thermally responsive lubricant disposed within by said wax lubricant; the openings of said porous support member, said and a sodium salt of a silicone resin sealant applied thermally responsive lubricant mass having low flow to all of the outer surfaces of the base Wheel except characteristics at ambient temperatures thereby to the circumferential surface to define an outer enremain substantially rigid with the support member velope adapted to retain the wax and phenyl methyl in such conditions and becoming fluid in the temsiloxane lubricant and to confine their expulsion perature range of 300 F. to 325 F. whereby when from the wheel to the circumferential surface area. the abrasive wheel is in use and is heated due to 3. In a rotatable self dressing diamond abrasive cupfrictional heat energy generated in abrasive use the shaped wheel adapted to carry and to dispense a therthermally responsive lubricant mass will become inmally responsive lubricant: creasingly more viscous in relation to its proximity a particle defined, porous, cupshaped support member to the Work surface defining a liowable mass when defining inter-particle openings and having a flaring elevated to a temperature in the range of 300 F. to wall terminating in a circumferential surface with 325 C. to flow out toward the circumferential sura frusto-conical recess defined about the outer peface of the support member and over the diamond riphery of the wall and extending to said circumparticle abrasive material, said support member ferential surface; adapted to be depleted at a significantly faster rate a diamond particle abrasive material mutually interthan the diamond abrasive in manner not to inhibit bonded and bonded to the recess of said wall to subsequent dispensing of lubricant whereby the cirdene an integral continuous section With the supcumferential surface of the support member always port member and defining a work engaging face in is coplanar with or lower than the work engaging juxtaposed relation to the circumferential surface; face of the diamond abrasive material. anda thermally responsive lubricant disposed Within References Cited in the me of this patent the inter-particle openmgs defined 1n the support member, said thermally responsive lubricant having UNITED STATES PATENTS low flow characteristics at ambient temperatures 980,882 Nichols Jan. 3, 1911 thereby to remain substantially rigid with the support 1,820,581 Richmond et al. Aug. 25, 1931 member in such conditions and adapted to ow relt, 2,009,222 Connor July 23, 1935 atively easy at high temperatures whereby when OO 2,194,546 Goddu etal. Mar. 26, 1940 the abrasive wheel Vis in use and is heated due to 2,225,193 Benner et al. Dec. 17, 1940 frictional heat energy generated in abrasive use the 2,746,220 Thomas May 22, 1956 thermally responsive lubricant mass Will become 2,942,387 Linblad lune 28, 1960 increasingly more viscous in relation to its proximity 5|, 2,947,206 Flanagan Aug. 2, 1960 to the Work surface to flow out toward the circumo 3,016,662 Ellis Jan. 16, 1962 

3. IN A ROTATABLE SELF DRESSING DIAMOND ABRASIVE CUPSHAPED WHEEL ADAPTED TO CARRY AND TO DISPENSE A THERMALLY RESPONSIVE LUBRICANT: A PARTICLE DEFINED, POROUS, CUP-SHAPED SUPPORT MEMBER DEFINING INTER-PARTICLE OPENINGS AND HAVING A FLARING WALL TERMINATING IN A CIRCUMFERENTIAL SURFACE WITH A FRUSTO-CONICAL RECESS DEFINED ABOUT THE OUTER PERIPHERY OF THE WALL AND EXTENDING TO SAID CIRCUMFERENTIAL SURFACE; A DIAMOND PARTICLE ABRASIVE MATERIAL MUTUALLY INTERBONDED AND BONDED TO THE RECESS OF SAID WALL TO DEFINE AN INTEGRAL CONTINUOUS SECTION WITH THE SUPPORT MEMBER AND DEFINING A WORK ENGAGING FACE IN JUXTAPOSED RELATION TO THE CIRCUMFERENTIAL SURFACE; AND A THERMALLY RESPONSIVE LUBRICANT DISPOSED WITHIN THE INTER-PARTICLE OPENINGS DEFINED IN THE SUPPORT MEMBER SAID THERMALLY RESPONSIVE LUBRICANT HAVING LOW FLOW CHARACTERISTICS AT AMBIENT TEMPERATURES THEREBY TO REMAIN SUBSTANTIALLY RIGID WITH THE SUPPORT MEMBER IN SUCH CONDITIONS AND ADAPTED TO FLOW RELATIVELY EASY AT HIGH TEMPERATURES WHEREBY WHEN THE ABRASIVE WHEEL IS IN USE AND IS HEATED DUE TO FRICTIONAL HEAT ENERGY GENERATED IN ABRASIVE USE THE THERMALLY RESPONSIVE LUBRICANT MASS WILL BECOME INCREASINGLY MORE VISCOUS IN RELATION TO ITS PROXIMITY TO THE WORK SURFACE TO FLOW OUT TOWARD THE CIRCUMFERENTIAL SURFACE OF THE SUPPORT MEMBER UNDER CENTRIFUGAL ACTION AND OVER THE DIAMOND MATERIAL, SAID PARTICLE DEFINED SUPPORT MEMBER ADAPTED TO BE DEPLETED AT A SIGNIFICANTLY FASTER RATE THAN THE DIAMOND ABRASIVE WHEREBY THE CIRCUMFERENTIAL SURFACE OF THE SUPPORT MEMBER ALWAYS IS COPLANAR WITH OR LOWER THAN THE WORK ENGAGING FACE OF THE DIAMOND ABRASIVE MATERIAL 